There is no applications folder per se in Linux. Open a shell and type "which <appname>", it'll show you where a specific program (that is in the path) is.
For example, on my machine here
which python
returns
/usr/bin/python
So /usr/bin is the applications directory --- in -this- case.
For example, on my machine here
which python
returns
/usr/bin/python
So /usr/bin is the applications directory --- in -this- case.